1. Field of the Invention
The present invention relates to an electronic controller having a front panel unit at which control elements are arranged which allow selection and incremental changes of controller process variables, step-wise selection of control parameters in the electronic controller and incremental changes of the values of the control parameters, and which has indicating devices by which the prevailing values of the process variables, the then selected control parameter and the value of the respectively selected control parameter can be indicated.
2. Description of the Prior Art
In a known electronic controller of this type (Equipment description "Microprocessor Control for Process Heating Applications", pages 1 to 19, Barber Colman Company, USA, Sept. 1979) it is possible to incrementally vary the process variables of a controller, for instance, the desired variable, and also the values of the control parameters, for instance, control gain and time constants, by means of control elements on a front panel unit. An indicating device with light-emitting diodes (LEDs) is suitable for the decimal display of the values of the control variables or the control parameters and another indicating device, such as a linear array of LED elements can identify the selected control parameter. The front panel unit of this known controller with its circuit parts is a fixed component of the overall system, so that the front panel unit and the controller housing form one unit. Changes in the values of the control parameters can be made at the front panel unit at any time, but improper use by unauthorized persons is not precluded.